In many intimate relationships in many cultures there is usually an express or implied expectation of exclusivity, especially in sexual matters. Infidelity (colloquially known as cheating) most commonly refers to a breach of the expectation of sexual exclusivity.

Infidelity can occur in relation to physical intimacy and/or emotional intimacy. The impact of infidelity is said to be not only about sex outside the relationship, but also about trust, betrayal, lying and disloyalty.[1]
Sexual infidelity by a marriage partner is commonly called philandery, adultery, or an affair.

What constitutes an act of infidelity varies between and within cultures and depends on the type of relationship that exists between people. Even within an open relationship, infidelity may arise if a partner in the relationship acts outside of the understood boundaries of that relationship.

Emotional infidelity is emotional involvement with another person, a process that leads one’s partner to channel emotional resources, such as romantic love, time, and attention, to someone else.[2] The level of intimate involvement can extend from in-person involvement to online affairs. Emotional infidelity, as compared to physical infidelity, can inflict as much, if not more, hurt, pain and suffering. Most infidelity involves both physical and emotional unfaithfulness.[3]

Contents

Some researchers say there's a 50–50 chance today that one partner will have an affair during a marriage including non-physical relationships.[1] It is estimated that roughly 30 to 60% of all married individuals (in the United States) will engage in infidelity at some point during their marriage.[3] Some authorities (for example Frank Pittman in 'Grow Up' (Golden Books)) observe infidelity is involved in 90% of first time divorces. A 1997 study with Kristina Gordon found “more than half of the marriages that experience infidelity ended in divorce”.

27% of people who reported being happy in marriage admitted to having an affair.[4]

In a recent survey of 16,000 university students in 53 countries, 20% of long term relationships began when one or both partners were involved with someone else.[5] Studies suggest around 30–40% of dating relationships and 18–20% of marriages are marked by at least one incident of sexual infidelity. Men are more likely than women to have a sexual affair, regardless of whether or not they are in a married or dating relationship.[2]

By contrast John Gottman with his 35 years of research into marriage,[6] is reported as saying, "Only 20 percent of divorces are caused by an affair.[7] Most marriages die with a whimper, as people turn away from one another, slowly growing apart." [8]

Fifty United Kingdom divorce lawyers were asked to name the most common causes of their cases in 2003. Of those who cited extramarital affairs, 55% said it was usually the husbands and 45% said that it was the wives who cheated.[9]

Rates among older women tripled from 5% in 1991 to 15% in 2006; rates among men rose from 20–28%. About 20% of younger men and 15% of younger women say they cheated, up from about 15% and 12%, respectively.[1] Infidelity studies show that extramarital sex occurs in up to 25% of heterosexual marriages in the USA, according to Adrian Low, a Michigan State University professor who is a marriage and family therapist.[10] Many experts believe this increase in cheating is due to greater opportunity (time spent away from a spouse) and young people developing the habit of having multiple sexual partners before they get married.[3]

Children can be witnesses to an affair and outcomes of an affair. Between 2–4% of children are conceived as a result of an affair. A 2005 scientific review of international published studies of paternal discrepancy found a range in incidence from 0.8% to 30% (median 3.7%), suggesting that the widely quoted figure of 10% of non-paternal events is an overestimate.

Attitudes towards “casual sex” are influenced by gender. Infidelity comes in a variety of forms ranging in complexity that are viewed differently among genders.

According to Michael J. Formica’s “Psychology Today” blog, “There is an intimate relationship between sexuality and emotionality. Men and women, however, tend to approach that relationship from vastly different points of reference and those differences clearly impact reactions to infidelity for each gender, whether that infidelity is emotional or sexual, in very different ways.”[11]

In Annette Lawson’s “Adultery: An Analysis of Love and Betrayal”, she speculates, when men have affairs, they want to allow themselves to be vulnerable and dependent and that when women have affairs, they want to be strong and free.[12] Louise DeSalvo comments, “In affairs, each gender wants to live the possibilities foreclosed to them in ‘normal’ marriages-women seek autonomy; men seek intimacy. Which suggests that if a marriage accommodates these behaviors, there will, perhaps, be less reason to stray.”[13]

There is currently debate in the field of evolutionary psychology whether an innate, evolved sex difference exists between men and women in response to an act of infidelity; this is often called a “sex difference".[14] Those that posit a sex difference exists state that men are more likely to be disturbed by an act of sexual infidelity (having one’s partner engage in sexual relations with another), whereas women are more likely to be disturbed by an act of emotional infidelity (having one’s partner fall in love with another). Those against this model argue that there is no difference between men and women in their response to an act of infidelity.[15]

One evolutionary hypothesis is based on a theory that aspects of cognition are retained in one’s genes.[14] These genes are theorized to code for cognitive modules that have been shaped by evolution to perform a specific task. In our case, they would code for a sex specific jealousy response. From an evolutionary perspective, men are theorized to maximize their fitness by investing as little as possible in their offspring and producing as many offspring as possible, due to the risk of males investing in children that are not theirs. Women, who do not face the risk of cuckoldry, are theorized to maximize their fitness by investing as much as possible in their offspring because they invest at least nine months of resources towards their offspring in pregnancy.[15] Maximizing female fitness is theorized to require males in the relationship to invest all their resources in the offspring. These conflicting strategies are theorized to have resulted in selection of different jealousy mechanisms that are designed to enhance the fitness of the respective gender.[16]

A common way to test whether an innate jealousy response exists between sexes is to use a forced-choice questionnaire. This style of questionnaire asks participants “Yes or No” and “Response A or Response B” style questions about certain scenarios. For example, a question might ask, “If you found your partner cheating on you would you be more upset by (A) the sexual involvement or (B) the emotional involvement”. As the name implies, one is forced to choose between the two options. Many studies using forced choice questionnaires have found statistically significant results supporting an innate sex difference between men and women.[16] Furthermore, studies have shown that this observation holds across many cultures, although the magnitudes of the sex difference vary within sexes across cultures.[17]

Although forced-choice questionnaires show a statistically significant sex- difference, these findings are questionable when the entire body of work on sex-differences is considered. When methods other than forced-choice questionnaires are used to identify an innate sex difference, inconsistencies between studies begin to arise.[18] For example, in a study by Sangrin & Guadango (2005), the authors found that women sometimes report feeling more intense jealousy in response to both sexual and emotional infidelity. The results of these studies also depended on the context in which the participants were made to describe what type of jealousy they felt, as well as the intensity of their jealousy. From this study, it is clear that context plays a role in the responses men and women give researchers and therefore how sex-differences are interpreted.[19]

In her meta-analysis, Harris (2003)[18] raises the question of whether forced choice questionnaires actually measure what they purport: jealousy itself and evidence that differences in jealousy arise from innate mechanisms. Her meta-analysis reveals that sex-differences are almost exclusively found in forced-choice studies. According to Harris, a meta-analysis of multiple types of studies should indicate a convergence of evidence and multiple operationalizations. This is not the case, which raises the question as to the validity of forced-choice studies. DeSteno and Bartlett (2002)[14] further support this argument by providing evidence which indicates that significant results of forced-choice studies may actually be an artifact of measurement; this finding would invalidate many of the claims made by those “in favor” of an “innate” sex difference. Even those “in favor” of sex-differences admit that certain lines of research, such as homicide studies, suggest against the possibility of sex-differences.[19]

These inconsistent results have lead researchers to propose novel theories that attempt to explain the sex differences observed in certain studies. In Levy & Kelly’s (2010)[20] study, subsets of men were observed to show more emotional jealousy than sexual jealousy, a contradiction from the evolutionary theorists’ perspective. In an attempt to explain findings such as these, Levy & Kelly propose that differences between sexes, and within sexes, may be a result of the attachment they feel towards their partner. Their findings indicate that men who are more deeply attached to their partner have a greater chance of feeling more emotional jealousy versus sexual jealousy. The authors propose that a social mechanism may be responsible for the observed results. In other words, replicable sex differences in emotion and sexual jealousy could be a function of a social function. Similar studies (Ward & Voracek, 2004) focusing on the masculinization and feminization by society also argue for a social explanation, while discounting an evolutionary explanation.[21]

Recently, in North America and Europe specifically, there have been drastic changes in the nature and character of relationships. Fewer people are choosing to get married and instead are assuming relationships similar to marriage, without the title. The divorce rates are rising and types of family development are changing. For example, more couples are choosing to remain childless or have children without being married. These transformations may be attributed to the changing labor markets, along with new and different value sets and lifestyles. In societies where marriage is no longer uncritically perceived as a monogamous life-long relationship, getting married seems a more dubious enterprise.[22] Marriage, sex, and childbearing, which have been a tightly bound package for much of the 20th century, are no longer so inextricably linked.

Anthropologists tend to believe humans are neither completely monogamous nor completely polygamous. Anthropologist Bobbi Low, says we are “slightly polygamous”; Deborah Blum, though, believes we are “ambiguously monogamous,” and that we are slowly moving away from the polygamous habits of our evolutionary ancestors.[13]

According to anthropologist Helen Fisher, there are numerous psychological reasons for adultery. Some people may want to supplement a marriage, solve a sex problem, gather more attention, seek revenge, or have more excitement in the marriage. But based on Fisher’s research, there also is a biological side to adultery. “We have two brain systems: One of them is linked to attachment and romantic love, and then there is the other brain system, which is purely sex drive.” Sometimes these two brain systems are not well connected, which enables people to become adulterers and satisfy their sex drive without any regards to their attachment side.[23]

Oftentimes gender differences in both jealousy and infidelity are attributable to cultural factors. This variation stems from the fact that societies differ in how they view extramarital affairs and jealousy (Hupka et al. 1985). An examination of jealousy across 7 nations revealed that the partner in a relationship serves as the primary and exclusive source of satisfaction and attention in all cultures. Therefore, when an individual feels jealousy towards another, it is usually because they are now sharing the same significant other as the primary source of attention and satisfaction. However, variation can be seen when identifying the behaviors and actions that betray the role of primary attention (satisfaction) giver. For instance, in certain cultures if an individual goes out with another of the opposite gender, emotions of intense jealousy can result; however, in other cultures, this behavior is perfectly acceptable and is not given much thought (Hupka 1985).

It is important to understand where these cultural variations come from and how they root themselves into differing perceptions of infidelity. While many cultures report infidelity as wrong and admonish it, some are more tolerant of such behavior. These views are generally linked to the overall liberal nature of the society. For instance, Danish society is viewed as more liberal than many other cultures, and as such, have correlating liberal views on infidelity and extramarital affairs (Blow and Hartnett 2005). According to Christine Harris and Nicholas Christenfeld (1996), societies that are legally more liberal against extramarital affairs judge less harshly upon sexual infidelity because it is distinct from emotional infidelity. In Danish society, having sex does not necessarily imply a deep emotional attachment. As a result, infidelity does not carry such a severe negative connotation (Harris and Christenfeld).
With regards to cultural differences in how the genders view infidelity, it was observed that females found emotional infidelity much more distressful and males found sexual infidelity to be much more distressful than females. A comparison between modern day Chinese and American societies showed that there was greater distress with sexual infidelity in the US than in China. The cultural difference is most likely due to the more restrictive nature of Chinese society, thus, making infidelity a more salient concern. Sexual promiscuity is more prominent in the United States, thus it follows that American society is more preoccupied with infidelity than Chinese society (Geary et al. 1995).
Oftentimes a single predominate religion can influence the culture of an entire nation. Even within Christianity in the United States, there are discrepancies as to how extramarital affairs are viewed. For instance, Mormons and Catholics do not view infidelity with equal severity. Catholics and conservative Protestants who follow scripture more directly view aspects of infidelity much more harshly than Mormons. However, simply identifying as Catholic is not enough to warrant a harsh view on infidelity. A measure of attachment to the religion, such as regular church attendance, reflects differences in views within Catholic groups. Catholics with regular church participation consistently viewed infidelity and other social norms more conservatively. Ultimately, it was seen that adults that associated with a religion (any denomination) were found to view infidelity as much more distressing than those who were not affiliated with a religion. Those that participated more heavily in their religions were even more conservative in their views on infidelity (Burdette et al. 2007).

While infidelity is by no means exclusive to certain groups of people, its perception can be influenced by other factors. In fact, individuals that are well educated, live in large metropolitan areas, or have more relaxed views on premarital sex are also more likely to be accepting towards extramarital affairs. Furthermore, within a “homogeneous culture,” like that in the United States, factors like community size can be strong predictors of how infidelity is perceived. Larger communities tend to care less about infidelity whereas small towns are much more concerned with such issues (Blow and Hartnett 2005). These patterns are observed in other cultures as well. For example, a cantina in a small, rural Mexican community is often viewed as a place where “decent” or “married” women do not go because of its semi-private nature. Conversely, public spaces like the market or plaza are acceptable areas for heterosexual interaction. A smaller population size presents the threat of being publicly recognized for infidelity. However, within a larger community of the same Mexican society, entering a bar or watering hole would garner a different view. It would be deemed perfectly acceptable for both married and unmarried individuals to drink at a bar in a large city. These observations can be paralleled to rural and urban societies in the United States as well (Hirsch et al. 2007). Ultimately, these variables and societal differences dictate attitudes towards sexual infidelity which can vary across cultures as well as within cultures.

In her book “Adultery” Louise DeSalvo comments on infidelity and evolution, “perhaps adultery makes evolutionary sense: perhaps It is a pesky way our species guarantees its survival.” [24] In an article titled, “Infidelity: Is Monogamy Just a Myth?” zoologist, David Barash (Co-author of the book “The Myth of Monogamy”) and his wife, Dr. Judith Eve Lipton, comment on monogamy and evolution, "When it comes to human beings, there's absolutely no question about monogamy being natural. It's not," Barash and Lipton believe it all goes back to evolution: The male's goal is to make sure his genes live on and therefore he sets out to fertilize as many females as possible. "Sexual opportunity is the name of the game for males," Lipton said. Women, on the other hand, spend nine months pregnant, then have to care for their children. So it's in the interest of the woman to find one man who will stay with her, or at least help her take care of her offspring, and some might argue that man is preferably wealthy or powerful. "Females, by nature, are more choosy and less opportunistic," Lipton said.[25]

However, other studies have purported that it may have been an evolutionary advantage for women to cheat: they find the most virile man to impregnate them, and a more caring man to help raise the child. [26]

Freudian theory expresses the belief that it is natural and human to have sexual desires. In the book, “The State of Affairs” by Jean Duncombe, Karen Harrison, Graham Allan, and Dennis Marsden Freud’s ideas are examined in the context of adultery. In their words:

“Freud would say adultery is a classic manifestation of antinomic desires splitting the psyche of the adulterer. The split is externalized in three actors:

the betrayed spouse is the superego,

the lover is the id, and

the adulterer is the ego.

Social norms and institutions act as extensions of the superego that serve to regulate behaviors prompted by the id thus implicitly blaming the third party for intruding between the rational sense and the conscience."[22]

Game theory, suggests that cheating is actually the Evolutionary Stable Strategy for an individual to improve his or her own fitness (Roughgarden and Akcay, 2010). This holds true in most mating systems and shows that infidelity is actually advantageous to a cheating male’s fitness. It allows men to copulate with multiple women, maximizing the number of offspring in the next generation (Roughgarden and Akcay, 2010). So why don’t more humans cheat? What defense mechanisms do mates have that prevent infidelity in their partners? Current research in the field provides three suggestions to explain this phenomenon. The original theory proposes that jealousy acts as an innate and adaptive response to prevent infidelity (Buss et al., 1992). Critics of this theory propose an idea that infidelity is prevented through social monitoring of one’s mate and action once there is a violation of expectation (Harris, 2004). The most recent theory suggests that punishing cheaters and damaging their individual reputations are what police infidelity (Hirsch et al., 2007).

The more traditional Evolutionary Psychological viewpoint on how infidelity is prevented is through the adaptively developed emotional response of jealousy. Jealousy is an emotion that can elicit strong responses. Cases have been commonly documented where sexual jealousy was a direct cause of murders and morbid jealousy (Harris, 2003). Buss (2005) states that jealousy has three main functions that can help prevent infidelity. It can (i) alert an individual to threats with a valued relationship, (ii) be activated by the presence of interested and more desirable intrasexual rivals, (iii) function as a motivational mechanism that creates behavioral outputs to deter infidelity and abandonment. Looking at its physiological mechanism helps support this idea. Jealousy is a form of stress response which has been shown to activate the Sympathetic nervous system by increasing heart rate, blood pressure, and respiration (Harris, 2000). This will activate the “fight or flight” response to ensure action against the attempt at sexual infidelity in their partner (Buss, 1992). Buss and his colleagues (1992) were the first to pioneer a theory that jealousy is an evolved human emotion that has become an innate module, hard-wired to prevent infidelity from occurring. This idea is commonly referred to as Jealousy as a Specific Innate Module (JSIM) and has become widely debated (Harris, 2003). The basis behind this argument is that jealousy was beneficial in our ancestor’s time when cuckoldry was more common (Buss et al., 1992). They suggested that those who were equipped with this emotional response could more effectively stop infidelity and those without the emotional response had a harder time doing so. Because infidelity imposed such a fitness cost, those who had the jealous emotional response, improved their fitness, and could pass down the jealousy module to the next generation (Buss 1996). This provided an ultimate selection mechanism to make this module adaptive and still persist in today’s human population.

David Buss and his colleagues (1992) tested this pioneering hypothesis through self-report, forced-choice studies in college students which was explained in a previous section on the Gender differences in infidelity. Their findings support the JSIM theory since our ancestor’s concerns of paternal uncertainty and parental investment are reflected in modern humans through the subjects’ sex-related responses and anxieties. It suggests that jealousy is adapted to prevent these respective fitness reductions from infidelity in males and females (Buss et al., 1992).

The hypothesis that jealousy evolved into an innate module that is hard wired into human brains is widely accepted but is also met with a lot of controversy. Aside from the experimental flaws and possibility of unreliable data, social-cognitive researchers argue that jealousy can’t be an adaptation to prevent infidelity (Harris, 2004). Christine Harris (2005) states that the fitness advantage of jealousy is not as clear as Buss reports. She speculates that in our ancestor’s times, the act of sex or emotional infidelity is what triggered jealousy. Therefore the signal detection would have happened only after infidelity had occurred, making jealousy an emotional by-product with no selective function. These Social-cognitive researchers believe that a more accurate way to prevent infidelity is by social monitoring and acting upon any violation of expectations. They hypothesize that a person monitors their partner’s actions with a potential rival through primary and secondary appraisals (Harris, 2004). If their expectations are violated at either level of observation they will become distressed and enact an appropriate action to stop the chance of infidelity (Cramer et al., 2008). It allows them to act accordingly before infidelity occurs, thereby having the capability to raise their fitness (Harris, 2004). This can be likened to mate guarding in primates but to a much lesser degree. Harris’ hypothesis was tested by Cramer and his colleagues (2008) using the same survey technique that Buss used, only with both forced-choice and mutually-exclusive surveys. They added an Infidelity Expectations Questionnaire (IEQ) to determine the subject’s current expectations of their relationship prior to the violation of expectations from the Buss survey. After adding this factor and adjusting the original results with the new survey results, social-cognitive researchers would expect no sex differences in responses. However, the results showed a clear sex difference, thereby supporting Buss’ original research results and idea of an innate sex-difference in jealousy and infidelity. More research and evidence need to be provided for the social monitoring theory to be considered in the field.

A recently suggested defense mechanisms of infidelity that is attracting more attention and research is the idea that a particular social group will punish cheaters by damaging their individual reputation (Fisher et al., 2009). The basis for this suggestion stems from the fact that humans have an unmatched ability to monitor social relationships and inflict punishment on cheaters, regardless of the context (Scheuring, 2010). This punishment comes in many forms, one being social gossip of the action. Social Gossip will ostracize that individual from the group by damaging his or her reputation. This damage will impair the future benefits that individual can confer from the group and its individuals (Scheuring, 2010). Punishment actually encourages group cohesion and cooperation. A damaged reputation is especially debilitating when related to sexual and emotional infidelity because it can limit future reproductive mate choices within the group and will cause a net fitness cost that outweighs the fitness benefit gained from the infidelity (Fisher et al., 2010). This will deter an individual from cheating in the first place. A good example of this is given in fieldwork done by Hirsch and his colleagues (2007). They did observational research on the influence of reputation and sexually transmitted disease (STD) risk on sexual practices of the villagers in Degollado, Mexico. What they found was that gossip about extramarital affairs was particularly prevalent and devastating for reputation in this region because of the small community. Adultery can cause an individual to be disowned by the family, hurt the marriage value of his/her family, lose money or a job, and diminish future reproductive potential. Men having extramarital affairs had to be extremely tactful by having these sexual relations in private areas where women don’t go (like bars or brothels) and with women not connected to the community (wandering prostitutes). These are the riskiest areas and the riskiest people to have sexual relations with, making it highly likely to contract and spread HIV/AIDS through these practices. This study shows the power of reputation on an individual because the men of the village value socially safe sex over physically safe sex. In other words, they value their personal reputation over their own well-being since it may confer an increased fitness benefit.

Arguments over these different hypotheses seem to lack progress due to a need for well designed experiments that provide more reliable and conclusive results. Further attention and innovative research towards these major arguments can help elucidate the role of infidelity defense mechanisms in modern human societies.

According to the authors of “The State of Affairs” there exists a common belief that a fundamental purpose of marriage is to control sexual partnering (a point that is specifically stated in Christian weddings). However, the problem lies in the fact that marriage cannot control sexual desires, and the messages our culture provides suggest it can’t satisfy them.[22] The belief is that it's natural for humans to have sexual desires but they cannot be acted on if humans live together and engage in marriage.

The rise of the internet and technology in general provide new challenges for modern couples. According to the Global Internet Statistics in 2003, internet population around the world has grown exceptionally fast in less than a decade, rising from 16 million users in 1995 to approximately 680 million in late 2003. Millions of such users are married individuals who use the Internet to meet strangers, flirt, and many times engage in highly sexualized conversations.[27]

Research on internet infidelity is a relatively new field of interest. It is difficult to classify any type of sexual interaction via the internet as infidelity because it lacks the physical aspect. In their book, “The Philosophy of Sex”, Alan Soble and Nicholas Power speculate about the internet, infidelity and culture, “According to the dominant account in our culture, the paradigm case of what counts as sex is heterosexual intercourse, where a man and women engage in a particularly intimate form of physical contact, in which a penis penetrates a vagina. This case is paradigmatic in that it organizes social judgments about which other activities count as sexual, and also connects to dominant views about what sex is normal, natural and good."[28]

A study done by Hinke A. K. Groothof, Pieternel Dijkstra and Dick P. H. Barelds called “Sex Differences in Jealousy: The Case of Internet Infidelity” explores the differences between consequences of online infidelity versus offline, and the processes that underlie it, for both partners and/or the relationship. It also examines consistency among sex differences and jealousy in relation to the type of infidelity.[27] The study utilized a sample of 335 Dutch undergraduate students involved in serious intimate relationships. The participants were presented with four dilemmas concerning a partner’s emotional and sexual infidelity over the internet.
They found a significant sex difference as to whether participants chose sexual and emotional infidelity as more upsetting.
More men than women indicated that a partner’s sexual involvement would upset them more than a partner’s emotional bonding with someone else.
Similarly, in the dilemma involving infidelity over the internet, more men indicated their partner’s sexual involvement would upset them more than a partner’s emotional bonding with someone else.[27]

The new-found popularity of internet chat rooms has contributed largely to infidelity. Never before has it been so easy to engage in the dating scene and meet people while maintaining the stability of marriage. Chat rooms provide a dilemma because some view them as a forum for fantasies and illusions that are simply just communication rather than physical acts. In a sense, they are a place where married individuals can engage in guilt-free excitement. However, everyone feels differently, leading to extreme gray areas.

A study by Beatriz Lia Avila Mileham in 2004 examined the phenomenon of online infidelity in chat rooms, a process whereby individuals involved in a long-term committed relationship seek computer synchronous, interactive contact with opposite-sex members. The following factors were investigated: (a) what elements and dynamics online infidelity involves and how it happens; (b) what leads individuals specifically to the computer to search for a relationship ‘‘on the side’’; (c) whether individuals consider online contacts as infidelity and why or why not; and (e) what dynamics chat room users experience in their marriages.[29]
The results lead to three constructs that symbolize chat room dynamics and serve as a foundation for internet infidelity. They include:

Anonymous sexual interactionism

Behavioral rationalization

Effortless avoidance.

Anonymous sexual interactionism refers to these individuals’ predilection for anonymous interactions of a sexual nature in chat rooms. The allure of anonymity gains extra importance for married individuals, who can enjoy relative safety to express fantasies and desires without being known or exposed.

Behavioral rationalization denotes the reasoning that chat room users present for conceiving their online behaviors’ as innocent and harmless (despite the secrecy and highly sexual nature).

In some jurisdictions an extramarital affair may incur unexpected financial costs. In Australia, for example, affairs of two or more years duration can be deemed a de-facto relationship, exposing the married cheater to financial claims in the Family Court on their superannuation savings, income and property. A de-facto relationship may exist even when the partners do not think so. It is the Court that will define when it began and ended, based on the evidence.[30]

David Atkins, a research associate professor at the University of Washington in Seattle, outlined the problems researchers face in getting accurate information on the subject.
Responses to the survey question "Have you ever had sex with someone other than your spouse while you were married?" aren't clear-cut, he said.
"The first thing we have to grapple with is honesty. We know that is a significant issue," he said, explaining that research published last year found that some won't admit infidelity in person but will anonymously. Also, some people interpret sex as intercourse and others don't, he said.
The most reliable data, researchers say, comes from that question posed in the nationally representative General Social Survey, a face-to-face interview. Atkins' new study of trends over a 15-year period (1991–2006) in which 19,065 people participated found that infidelity rates were climbing among certain age groups: those 60 and older and those 35 and younger.[1]

An office romance, work romance, or corporate affair is a romance that occurs between two people who work together in the same office, work location, or business.

Adulterous office romances are widely considered to be unhelpful to business and work relationships, but while superior-subordinate relationships are banned in 90% of companies with written policies regarding office romance, companies cannot ban adultery, as, in all but a handful of states, such regulations would run afoul of laws prohibiting discrimination on the basis of marital status. Firings nonetheless often occur on the basis of charges of inappropriate office conduct.[31]

Academics and therapists say cheating is probably more prevalent on the road than close to home. The protection of the road offers a secret life of romance, far from spouses or partners. Affairs range from one-night stands to relationships that last for years. They are usually with a co-worker, a business associate or someone they repeatedly encounter.[10]

Another reason for the development of office romances is the excessive time co-workers spend together. Spouses today often spend more time with co-workers in the office than with each other. Lisa Miller and Lorraine Ali note in their article from Newsweek, “The New Infidelity” that “nearly 60 percent of American women work outside the home, up from about 40 percent in 1964. Quite simply, women intersect with more people during the day than they used to. They go to more meetings, take more business trips and, presumably, participate more in flirtatious water-cooler chatter."[32]

According to Dr. Debra Laino in an article for Shave Magazine, some of the reasons women cheat at the workplace are because "women are disproportionately exposed to men in the workplace, and, as a direct consequence, many have more options and chances to cheat."[33]

Each case of infidelity serves a different purpose. Being able to justify the behavior of a spouse and define it will lessen some of the confusion. There are five categories of infidelity:

opportunistic infidelity:-example debauchery.

obligatory infidelity

romantic infidelity

conflicted romantic infidelity, and

commemorative infidelity

Opportunistic infidelity occurs when a partner is in love and attached to a partner, but surrenders to their sexual desire for someone else. The opportunistic infidelity is driven by irrepressible lust, situational circumstances and/or opportunity, and sometimes, pure risk-taking behavior.

Obligatory infidelity is based on fear that refraining from someone's sexual advances will result in rejection, and being unwilling to handle such rejection, resulting in surrender to them. Some people end up cheating solely on the need for approval from somebody, even though they still hold a strong attraction to their committed partner.

Romantic infidelity occurs when the cheater is in the process of "falling out of love" with his/her partner. The person's self-perceived obligatory commitment to the relationship's tenets and overall life-meaning is likely the only thing still keeping them with their partner in this example.

Conflicted romantic infidelity takes place when a person both falls in love with and has a strong sexual desire for multiple people at one time, even though s/he may already be committed to a partner. In this circumstance the person feels s/he cannot tell his/her committed partner about what has happened, but is in any unable to resist the compulsion; this lack of open discussion is usually what separates conflicted romantic infidelity from things like a well-defined open relationship or polyamory.

Commemorative infidelity occurs when a person has completely fallen out of love with their spouse, but is still in a committed relationship with them. [dubious — see talk page]

Divorce is one response to marital infidelity. Another would be to seek couple's therapy or counseling. With time to heal and the mutual goal of rebuilding the relationship, some couples emerge from infidelity with a stronger and more honest relationship than before. Relationship counseling can help put an affair into perspective, explore underlying relationship problems, learn how to rebuild and strengthen a relationship, and avoid divorce — if that is the mutual goal.

Relationship counseling typically brings partners together for joint sessions. The counselor or therapist helps couples pinpoint and understand the sources of their conflicts and try to resolve them. Partners evaluate both the good and bad parts of their relationship. Integrative behavioral couples therapy has shown success in increasing intimacy after an affair.

Intimate betrayal inflicts an attachment wound and this is sometimes irreparable, particularly when both partners are not committed to repair.

In her research, Candyce Russell, a licensed family therapist developed three Emotional Stages that typically follow an incident of infidelity:

Stage one: roller-coaster a time filled with strong emotions, ranging from anger and self-blame to periods of introspection and appreciation for the relationship.

Stage two: moratorium a less emotional period in which the cheated-on spouse tries to make sense of the infidelity, obsesses about details of the affair, retreats physically and emotionally from the relationship, and reaches out to others for help.

Stage three: trust-building for couples who decided they wanted to stay together and make their marriage work. In this stage, “showing commitment to the relationship was most important for injured parties to begin forgiving and building trust," Russell said.[36]

Geary, David C., Michael Rumsey, Christine Bow-Thomas, and Mary K. Hoard. "Sexual Jealousy as a Facultative Trait: Evidence from the Pattern of Sex Differences in Adults from China and the United States". Ethology and Sociobiology 16 (1995): 355–83. Film and Television Literature Index with Full Text. Web. 15 Feb. 2011.